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1500 questions
12
votes
5 answers
What is the definition of DX?
I always believed that DX meant out of one’s own country, and in the continental US that can be pretty far. However, tooling around on the bands I’ll often hear people calling DX inside the US receive responses from others also inside the US.…
Adam Davis
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votes
2 answers
Why say "break" and "over" on walkie-talkies instead of an automatic chirp?
My understanding of why movie characters say "break" and "over" during radio conversations is based on this answer, which says that people using half-duplex devices often will want to let others on the channel interrupt them with something more…
Ryan
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12
votes
4 answers
Capacitive hats on wire dipoles?
Capacitive hats seem to be advertised as an option for mobile vertical antennas. One mentioned advantage is the they can widen the SWR bandwidth, making the antenna easier to tune.
What might be the effect of using capacitive hats, not on a mobile…
hotpaw2
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12
votes
7 answers
Can I transmit anything inside a Faraday cage?
Can I perform any transmission regardless of my license as long as I'm inside an RF sealed enclosure, such that no RF will be detectable from my transmissions off my property?
I imagine the answer is yes, but I'd like to be sure I understand.
Adam Davis
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12
votes
3 answers
What does the spark-gap do in a spark-gap transmitter?
I read the Wikipedia article about spark-gap transmitters and I have to admit that I’m even more confused as to what the spark-gap actually did.
The article references this simplified circuit diagram:
So it seems to me (and correct me where I’m…
RoboKaren
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12
votes
3 answers
Why can't I hear myself from a second radio when bouncing off a repeater?
I am a relatively new ham, and haven't joined any club yet or participated in any nets. I have, however, hit a repeater just to know I can do it. I was told my sound was scratchy (no surprise there) but I want to hear how bad it is. I tried…
Bernem-KG7NUB
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12
votes
3 answers
What is the best practice when tuning an antenna on air?
I have a magnetic loop antenna that takes a long time to tune and of course, while tuning it, I need to be transmitting.
What is the best procedure for tuning on air? I understand I need to check the frequency and identify myself before…
David VK2VXK
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12
votes
2 answers
What are the (US) rules about unlicensed low-power transmissions?
It is common wisdom that transmissions of any sort (perhaps unidentified, encrypted, in the FM broadcast band, etc.) are permitted if they are sufficiently low power.
Where are the FCC regulations which permit this, or where can I find a…
Kevin Reid AG6YO
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12
votes
5 answers
Does an amateur radio licence work worldwide?
Lets say that I get my amateur radio license in country A and then some time later I move to country B. Will I need to get a new license on country B or does the license obtained in country A works just fine?
kR105
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11
votes
2 answers
Why do satellites receive and transmit on different bands?
Most satellites I've found transmit on VHF and receive on UHF or vice versa. Why is this? I would think there's enough space on a single band.
Skyler 440
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11
votes
6 answers
Key CW on zero crossings - zero bandwidth?
I remember being surprised to learn that a CW signal has a bandwidth (albeit small), but when I thought it over, it made sense. Essentially, we are modulating the carrier with a low frequency square wave. This would explain key clicks: a perfect…
Dominick Pastore
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11
votes
1 answer
Is FM modulation still more resistant to noise when given the same bandwidth as an AM signal?
FM modulated radio is much more resistant to noise and can deliver better sound quality than AM radio. But FM signals also use more bandwidth than AM signals. In general a wider bandwidth signal is more resistant to noise / can send more data than a…
JanKanis
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11
votes
1 answer
What is body blocking, and does it work with a stock HT on a foxhunt?
I've heard that you might not need a special directional antenna to participate in a foxhunt, that some people are able to use their body to help determine the direction of a signal.
How does this work? More specifically, what is the process to do…
Adam Davis
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11
votes
2 answers
Can an amateur use cellular technologies with SDR?
Software Defined Radio is opening up many new possibilities for amateur digital modes. One family of technologies that interests me is cellular. 2G GSM voice/sms and 2.5G GPRS data has been proven to work with OpenBTS on a USRP SDR using licensed…
JC Hulce
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11
votes
1 answer
Tuning a wire antenna by folding
Last weekend we tuned a quad loop for 80 m and 40 m. Instead of cropping, we folded the isolated wire using cable ties as shown in the picture below.
After folding several quite large sections of the wire, we got the SWR under 1.2, so this approach…
koalo
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